A cutoff frequency of a filter implemented in an integrated chip may change according to a variation of a manufacturing process or a temperature. Thus, a filter tuning system is required for compensating for the changed cutoff frequency. The filter tuning system performs a function of maintaining the time constant of the filter that changes according to the variation of the manufacturing process or the temperature.
A conventional filter tuning system detects the time constant of the filter to compare the detected result with a reference value. Then, the filter tuning system counts up/down based on the comparison result. When an error between the detected time constant and the reference value is relatively large, it may take a long time to count up/down to a predetermined level. In addition, as the filter tuning system has a high resolution and a small calibration interval, it may take a longer time to count up/down to the predetermined level.